Ha Observations of the Binary System VV Cephei Ernst Pollmann

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Ha Observations of the Binary System VV Cephei

Ernst Pollmann
ASPA
Active Spectroscopy in Astronomy
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VV Cephei 4,9 mag
µ Cephei 4,0 mag
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The orbit of the Be-star Gasdisk leads to the
eclipse by the M-type star Duration
of eclipse 673 days
Periode 20,4 years
M2Iab Supergiant 2-3 Solar masses 1600 Solar
radii
Last eclipse Jun/1996 August/1998
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Rotating Hydrogen-Gasdisk and its hot
Be-Star with 8 Solarmasses
red shiftet
blue shiftet
Observer
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Time behavior of the Ha-emission since 1996 until
today
Eclipse 1997-99
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V/R of the Ha-emission as function of orbital
phase
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08/199401/2015
09/1999
09/2003
11/2009
Periastron passage
10/2004
11/2005
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Increase of the emission strength by mass
overflow into the Be-disk at periastron
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Ha observations on the Be binary ? Tauri First
some introduction wordsasking for
patienceErnst PollmannASPA Active
Spectroscopy in Astronomy
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The binary system z Tau

• Development of a rotating one-armed density wave
  by disturbed orbits
• Due to a radial disturbance the gas particles
  of the disk are moving on excentric Kepler-orbits

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Temporal development of the Ha-profile
? (2003/09 to 2007/03) Dispersion 27?/mm R
?/D? 14000
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Temporal development of the Ha-profile between
2000 and 2006 All Profiles from 2000-2006. The
vertical offset is proportional to time and
corresponds to 25 days per continuum unit. The
lowermost spectra date from Nov./2000 (left),
Sep./2002 (middle) and Aug./2004 (right). The
spectra are published electronically in the form
of ASCII-tables IBVS-Nr. 5813
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Ha equivalent widths of ? Tau since 1975
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Enlargement of the previous figure showing the
data presented in this work in greater detail,
also for comparison between values taken with
professional and amateur equipment.
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• Development of a rotating one-armed density wave
  by disturbed orbits
• Due to a radial disturbance the gas particles of
  the disk are moving on excentric Kepler-orbits
• This leads to V/R-variations
• V/R of Ha show the same period as the radial
  velocies
• Period duration 1500 d

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Ha V/R-ratio
The residuals of the left panel, folded with P
69.3 d and the respective sine fit. Shown are 1.4
cycles for clarification, i.e. 40 of the points
are redundant.
The measured values vs. Julian date (open
symbols) and the sine wave with P 1471 d (plus
signs).
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Causes of the V/R variations

• V/R variations in binary stars may be locked to
  the orbital phase
• follow quasi-cyles typical 5-10 years
• or combines these two types of variations with
  long-term trends
• length and amplitude of the quasi-cycle vary from
  cycle to cycle

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Questions of the V/R variations

• Conditions of the synchronisation of the V/R
  variations with the orbital periods ?
• Several peculiarities of emission lines and their
  profiles can hardly be explained with one-armed
  oscillation model

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Phase variations of the radial velocity of the
HeI line 6678 and Ha-V/R (1)
(1) Stefl/Okazaki/Rivinius/Baade V/R-
Variations of binary Be stars (ASP-Conference
Series, Vol. 361, 2007)
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Radial velocity of the HeI line 6678?
Long term Period 1503 d ?
Radialgeschwindigkeit km/s
Gemeinschaftsprojekt R. Bücke, Hamburg / E.
Pollmann, Leverkusen
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thanks for attention
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